Number of active U.S. drilling rigs down this week

HOUSTON, Aug. 18 (Xinhua) -- The number of active drilling rigs in the United States dropped to 642 this week, down by 12 from the previous week and by 120 from one year ago, according to the weekly data released Friday by Houston-based oilfield services company Baker Hughes.

These active drilling rigs included 520 oil rigs operating in U.S. oil fields, down by five from the previous week; 117 gas drilling rigs,